Abnormalities of the proximal and distal radioulnar joints (DRUJ) are commonly encountered in clinical practice in association with trauma or dislocation, synovial inflammatory diseases, or congenital abnormalities and may be associated with numerous conditions, including ulnar styloid fracture, Colles fracture, radial diaphyseal fracture, radial head fracture or excision, triangular fibrocartilage complex injury, and disproportionate radioulnar length. The diagnosis of DRUJ abnormalities is difficult, however, since limitations of conventional radiologic imaging procedures make it difficult or impossible to radiographically confirm subluxation or dislocation of the DRUJ. Abnormalities of the DRUJ may, therefore, go undiagnosed.
Computed Tomography (CT), however, can be used to image the DRUJ. Since CT delineates the cross-sectional anatomy of the DRUJ, this technique can be utilized for the evaluation of the anatomy and mobility of the DRUJ, as well as for suspected joint subluxation. However, a number of problems have also been associated with attempts to diagnose abnormalities of the DRUJ using CT. First, prior art evaluation protocols do not provide a means for positioning the right and left upper extremity in a consistent fashion. Typically, the forearms are simply placed in the CT gantry with the wrists at approximately the same level, and the patient is asked to rotate the forearm into maximum pronation (palm down) and supination (palm up) positions. Thus, the wrists may be at different levels and the forearms may be at different degrees of rotation within the scan. Because the location of the forearms and wrists are not consistent, it is necessary to obtain a large number of images, in order to insure that the same regions of both wrists are imaged. Because of the large number of images acquired, the patients are exposed to a significant degree of radiation. Furthermore, when both forearms are not positioned in the same degree of rotation, it is not possible to compare a left and right wrist or forearm. Additionally, even though most patients complain of their most severe symptoms while actively using their upper extremities, prior art methods do not provide a means for simulating or generating resisted rotation.
There remains a need, therefore, for a method and apparatus for consistently positioning and rotating a forearm for purposes of imaging and evaluating the forearm joints.